This invention pertains to remediation compositions and methods for cleaning contaminated soils, contaminated ground water and foul air emanating from contaminated sites. More particularly, this invention pertains to remedial compositions comprising TRITON(trademark) surfactants, and processes using these compositions for cleaning sites contaminated with petroleum-based and organic compounds.
Soil and ground water contaminations are frequent and often found around automotive garages, under heating oil storage tanks, near manufacturing plants, paint shops and in parking areas of industrial machinery for examples. The contaminants found at these locations are various and include in most cases hydrocarbons such as paint thinner, gasoline, fuel, kerosene, lubricants, bunker C oil and even pitch. In other words, the range of contaminants commonly found in contaminated soils and ground water contains numerous petroleum products including polycyclic aromatic hydrocarbons (PAH""s). These are the contaminants that are of interest herein, and are often referred to hereinafter as Light Non-Aqueous Phase Liquids (LNAPL contaminants).
In the past, various methods have been used for cleaning soils contaminated with petroleum-based and organic contaminants. One of the best known method is referred to in the art as an xe2x80x9cex-situxe2x80x9d process which includes excavation and transport of the contaminated soil, and treatment of this soil at a remote location. A second best known method is an xe2x80x9cin situxe2x80x9d process, which comprises the steps of leaching a remediation solution through a contaminated soil and pumping out the solution containing the emulsified contaminants, from one or more wells reaching below the contaminated region. Examples of in situ and ex-situ remediation processes are described in the following patents:
U.S. Pat. No. 4,869,825 issued on Sep. 26, 1989 to W. Steiner;
U.S. Pat. No. 4,997,313 issued on Mar. 5, 1991 to T. L. Gibson et al.;
U.S. Pat. No. 5,011,329 issued on Apr. 30, 1991 to J. M. Nelson et al.;
U.S. Pat. No. 5,035,537 issued on Jul. 30, 1991 to J. L. Rose;
U.S. Pat. No. 5,160,217 issued on Nov. 3, 1992 to N. Metzer et al.;
U.S. Pat. No. 5,161,914 issued on Nov. 10, 1992 to P. L. Rahn et al.;
U.S. Pat. No. 5,249,888 issued on Oct. 5, 1993 to K. E. Braithwaite et al.;
U.S. Pat. No. 5,263,795 issued on Nov. 23, 1993 to J. C. Corey et al.;
U.S. Pat. No. 5,342,147 issued on Aug. 30, 1994 to F. C. Payne et al.;
U.S. Pat. No. 5,449,251 issued on Sep. 12, 1995 to W. D. Daily et al.;
U.S. Pat. No. 5,509,760 issued on Apr. 23, 1996 to F. E. Schriefer et al.;
U.S. Pat. No. 5,553,974 issued on Sep. 10, 1996 to D. Nazarian;
It is believed that the most commonly used in situ remediation process is as disclosed in the U.S. Pat. No. 4,997,313 mentioned above. In this process, an aqueous surfactant solution is applied to the soil and is allowed to penetrate the soil and leach through the contaminated region. The leachate is removed from a recovery well at the middle of the contaminated region. Pumping is done at a rate of about twice the flow of injection of the remediation solution to the soil so as to reduce the water level in the region of the well, to induce a flow of leachate from the above soil formation into the well. This in situ method is also referred to as a xe2x80x9cpump-and-treatxe2x80x9d process wherein the leachate and the contaminated ground water are pumped from the underground to the surface and treated to separate the contaminants. The treated ground water is then returned underground.
The prior art also contains several emulsifier and surfactant compositions for cleaning a contaminated soil, whether the method is carried out in situ or ex-situ. Examples of remediation compositions of the prior art are found in the following patents:
Canadian Patent Application 2,089,639, published on Feb. 14, 1993 by L. M. Purcell et al.;
U.S. Pat. No. 5,156,686 issued on Oct. 20, 1992 to D. C. Van Slyke;
U.S. Pat. No. 5,252,138 issued on Oct. 12, 1993 to E. P. Guymon;
U.S. Pat. No. 5,376,183 issued on Dec. 27, 1994 to S. Gatt et al.;
U.S. Pat. No. 5,525,008 issued on Jun. 11, 1996 to J. T. Wilson.
It is also known that some of the soil remediation compositions of the prior art contain one or more of the TRITON(trademark) surfactants or their chemical equivalents. TRITON(trademark) surfactants are manufactured by Union Carbide Corporation from Danbury, Conn. USA. The following patents are specific examples of remediation compositions containing one or more of the TRITON surfactants.
Canadian Patent 1,322,862 issued on Oct. 12, 1993 to T. Cseh et al.;
Canadian Application for Patent 2,042,599 published on Apr. 11, 1991 by B. E. Peacock;
U.S. Pat. No. 5,154,831 issued on Oct. 13, 1992 to S. T. Darian et al.;
U.S. Pat. No. 5,286,386 issued on Feb. 15, 1994 to S. T. Darian et al.;
U.S. Pat. No. 5,306,351 issued on Apr. 26, 1994 to W. J. Anderson;
U.S. Pat. No. 5,427,688 issued on Jun. 27, 1995 to T. M. Sivavec;
U.S. Pat. No. 5,634,983 issued on Jun. 3, 1997 to N. Kammeraad;
U.S. Pat. No. 5,660,613 issued on Aug. 26, 1997 to R. L. Bernier et al.;
U.S. Pat. No. 5,711,020 issued on Jan. 20, 1998 to N. L. Wolfe et al.;
U.S. Pat. No. 5,817,187 issued on Oct. 6, 1998 to T. F. D""Muhala et al.;
U.S. Pat. No. 5,922,665 issued on Jul. 13, 1999 to A. Liu;
U.S. Pat. No. 5,928,433 issued on Jul. 27, 1999 to R. W. Jahnke et al;
In the past, the in situ or pump-and-treat remediation method has been preferred to the ex-situ process, basically for cost consideration and for not disrupting the terrain. However, these in situ methods are generally tedious, can require years to perform, and may never fully return the soil and ground water to an acceptable condition to serve as a drinking water aquifer.
Therefore, it is believed that a continuing need exists in the art for remediation compositions and accompanying methodology, to clean contaminated soils and ground water more efficiently, reliably, economically and safely than has heretofore occurred with conventional methods.
The present invention provides for remediation compositions and solutions which have excellent contaminant-emulsifying capacities for cleaning contaminated sites quickly, thoroughly and economically. The remediation solutions of the present invention have a very low eco-toxicity and are biodegradable in a relatively short time. The present invention also provides for methods for cleaning contaminated soils, contaminated ground water and air emanating from a contaminated site.
Broadly, in accordance with one aspect of the present invention there is provided a remediation composition for cleaning a soil mass and/or ground water contaminated with an organic contaminant. The remediation composition comprises an aqueous carrier, a first surfactant having a first contaminant-emulsifying capacity mixed with the aqueous carrier, and a second surfactant having a second contaminant-emulsifying capacity, mixed with the aqueous carrier and with the first surfactant. The first surfactant is TRITON X-100 and the second surfactant is selected from a group of surfactants consisting of TRITON X-155 and TRITON X-190.
In use, in presence of certain hydrocarbon contaminants, a total contaminant-emulsifying capacity of the remediation composition is greater than a sum of the contaminant-emulsifying capacities of the first and second surfactants alone in the aqueous carrier. In some cases, the contaminant-emulsifying capacity of the remediation composition has been found to be about three times as much as the sum of the contaminant-emulsifying capacities of the first and second surfactants alone in the aqueous carrier.
In further aspects of the present invention, three basic remediation compositions have been formulated for cleaning soils and ground water contaminated with a wide range of LNAPL contaminants. The three broad formulas are as follows:
a) When the contaminant contains a light range hydrocarbon, including PAH""s, the remediation composition comprises per weight in an aqueous carrier:
TRITON X-100: 1%;
TRITON X-155: 1%;
TRITON X-190: 0.5%;
TRITON X-45: 0.2%, and
TRITON X-35: 0.2%.
b) When the contaminant contains a middle range hydrocarbon, the remediation composition comprises per weight in an aqueous carrier:
TRITON X-100: 1%;
TRITON X-155: 1%;
TRITON X-190: 0.2%;
TRITON X-45: 0.5%, and
TRITON X-35: 0.05%.
c) When the contaminant contains a heavy range hydrocarbon, the remediation composition comprises per weight in an aqueous carrier:
TRITON X-100: 1%;
TRITON X-155: 1%, and
TRITON X-190: 1%.
In another aspect of the present invention, there is provided a remediation composition which comprises an aqueous carrier, a first surfactant having a first solubility with the aqueous carrier, mixed with the aqueous carrier, and a second surfactant having a second solubility with the aqueous carrier, mixed with the aqueous carrier and with the first surfactant. The first surfactant is TRITON X-100 and the second surfactant is selected from a group of surfactants consisting of TRITON X-15, TRITON X-35 and TRITON X-45. In this composition, the miscibility of the second surfactant in the composition is greater than its solubility with the aqueous carrier alone.
In another aspect of the present invention, the remediation compositions are mixed with purging water in a proportion of about 1,000 to 1,100 parts of purging water for one part of a total of the aqueous carrier and the surfactants. The remediation solutions thus obtained have a very low eco-toxicity, are highly biodegradable, and still have an exceptional emulsifying capacity for LNAPL contaminants. As will be understood, the term remediation solution is used herein to designate a remediation composition according to the present invention in a diluted form with purging water.
In yet another aspect of the present invention, there is provided a method for in situ cleaning a soil mass contaminated with an organic contaminant and ground water associated with this soil mass. The method comprises the steps of defining a location of the contaminant in the soil mass; defining a static level of the ground water relative to the soil mass and the contaminant; if the contaminant is at proximity of the ground water table, defining the thickness of a contaminated smear zone due to static level variations in the ground water table, and injecting a remediation solution in the soil mass until the level of the ground water rises above its static level, above the contaminant and above the contaminated smear zone, thereby allowing the remediation solution to soak into the contaminant for encapsulating therein portions of the contaminant. When the remediation solution has completely covered the contaminant, pumping of the remediation solution and of the ground water from the soil mass is effected until the level of the ground water is below the static level and the contaminant. The remediation solution and the ground water are then treated for extracting the contaminant therefrom. The raising and lowering of the water table are effected repeatedly until the contaminant has been washed out from the soil mass and ground water to an acceptable level. This method is particularly advantageous for quickly and simultaneously cleaning a soil mass and ground water associated with the soil mass.
In yet a further aspect of the present invention, there is provided a method for ex-situ cleaning a contaminated site. This particular method comprises the step of providing an apparatus having a soil-receiving compartment, an array of pipes and nozzles disposed above the soil-receiving compartment and a drain compartment disposed below the soil-receiving compartment. The method also includes the steps of excavating a soil mass from a designated portion of a contaminated site, transferring this soil mass into the soil-receiving compartment of the apparatus, and applying to the soil mass a remediation composition comprising TRITON X-100 and one surfactant selected from a group of surfactants consisting of TRITON X-155 and TRITON X-190. After cleaning of the soil mass, it is returned to the site as backfill for example.
This method is particularly efficient for cleaning a site ex-situ without transporting the contaminated soil over great distances. This method is also efficient for cleaning a contaminated site systematically one portion at the time while monitoring a level of contamination in each portion before and after the remediation process.
In still a further aspect of the present invention, there is provided a method for reducing an emanation of volatile contaminants from a site contaminated with an odorous organic contaminant. This method comprises the step of applying to the contaminated site a remediation composition comprising TRITON X-100 and one surfactant selected from a group of surfactants consisting of TRITON X-155 and TRITON X-190. The volatile contaminants are thereby solubilized and retained to the remediation composition to reduce emanations of foul air from the contaminated site before and during a remediation process for example.
Still another feature of the present invention is that the remediation compositions are susceptible of a low cost of manufacture with regards to both materials and labor, and which accordingly are then susceptible of low prices of sale to the industry, thereby making remediation efforts economically available to the public.